Try searching "camellia bud drop" for possible causes.

Camellias, like hibiscus, are persnickity plants. What zone are you in? Are they in shade or sun (they don't like to be in full sun)? How are they watered? Have you had any cold weather?

Thank you for your comments. They are helpful. We live in Tampa, FL and every December the tree produces beautiful flowers just in time for Christmas. But the flowers don't stay on the tree as long as they should. It is not unusual for the temperature to dip into the low thirties at this time of year. The tree gets about 1 hour of morning sun in the winter, about 2 hours of morning sun in the warmer months. It is watered twice/week by our sprinkler system. I will check the soil to see if it is too moist. I don't see any pests on it. I may have to accept that this beautiful plant is indeed persnickety!

This happens when the temps get too high. There are also varieties that do better in warmer climates such as ours. If you have a variety that is common further North that may be the cause. My bushes are also loaded, a few have opened but I'm worried with this unusually warm weather that I will also have a problem with the bull-nosing.